The invention relates to a method of stopping a motor vehicle without jolting as well as to a control unit for such a method.
The functionality of jolt-free stopping (“soft stop”) of a motor vehicle has hitherto been realized only in so-called electrohydraulic brake systems.
In an electrohydraulic or power-actuable brake system, the driver request at the brake pedal is detected by means of sensors and supplied in the form of electrical signals to an electronic controller that controls an electric brake pressure generator (“brake by wire” mode). In order even in the event of failure of the vehicle electrical system still to be able to brake the motor vehicle with a minimum deceleration, the electrohydraulic brake system additionally has a redundant hydraulic emergency braking functionality, which may act directly and without any kind of electronic control upon the brakes of the vehicle wheels. In the case of this hydraulic emergency braking functionality, in a conventional manner by means of a foot-force-actuable brake pressure generator and hydraulic lines a direct connection is established between the brake pedal and the wheel brakes of the motor vehicle (“push-through” mode).
In the case of the soft stop functionality, shortly before reaching the stationary state of the vehicle the pressure acting upon the wheel brakes is automatically reduced. Thus, the vehicle jolt that arises upon reaching the stationary state of the vehicle is at least minimized because the—compared to the sliding friction—higher static friction of the brake linings is compensated by a lower brake pressure. In the case of an electrohydraulic brake system, in the normal “brake-by-wire” mode the driver is uncoupled from the brake system because of the existence of the simulation piston. The soft stop functionality in an electrohydraulic brake system accordingly does not make itself felt in the response characteristic of the brake pedal.
An object of the present invention is to provide a soft stop functionality in a foot-force-actuable brake system.